1. Field of the Invention
The present invention pertains to an adjustable orifice fitting carrier assembly for measurement of flow through a pipeline. In particular, the present invention pertains to an orifice fitting carrier assembly that may be adjusted to concentrically align the center orifice with the axis of the pipeline while the carrier assembly is in the fitting.
2. Prior Art
The flow of natural gas or other fluids through a pipeline may be measured by placing a restriction, such as an orifice plate, within the pipeline in order to cause a reduction in pressure or pressure drop as the fluid flows through the opening in the orifice plate. The pressure of the fluid drops abruptly as it flows through the orifice and it reaches a minimum value a short distance beyond. There is a relationship between the amount of this pressure drop and the rate of gas or fluid flow through the opening in the orifice plate. Pressure connections for attaching a differential gauge on both sides of the orifice plate are provided to measure the difference in pressure.
Periodically, because of wear and for other reasons, it will be necessary to remove and replace the orifice plate retained within the fitting. When the orifice plate is installed, the axis of the opening of the orifice plate must be at the center of the pipeline. The concentric positioning of the orifice plate is required to achieve an accurate flow measurement and because of regulations which require the concentric alignment. Additionally, regulations such as those recently promulgated by the American Petroleum Institution set forth the relative positioning of the orifice fitting to the carrier which holds the orifice plate. For example, the internal diameter of the carrier must not vary significantly from the diameter of the fitting.
There is a need, therefore, to provide a mechanism for the vertical and horizontal adjustment of the carrier assembly to permit concentric alignment of the bore of the orifice fitting with the pipeline.
It is a principal object and purpose of the present invention to provide a mechanism for the vertical and horizontal adjustment of the orifice plate to permit concentrical alignment of the bore of the orifice fitting with the pipeline.
It is an additional object and purpose of the present invention to provide a mechanism for vertical and horizontal adjustment of the carrier plate while the carrier assembly is in the field and within the orifice fitting.
It is a further object and purpose of the present invention to provide an adjustable carrier assembly to be used with existing orifice fittings.